We used the electrospray deposition (ESD) method to fabricate organic photovoltaic devices with poly (3-hexyl-thiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) blends of different composition ratios and different organic solvent solution, namely chloroform (CLF) and dichlorobenzene (DCB). The morphology and crystallinity of the active layers were investigated by means of atomic force microscopy (AFM), two-dimensional X-ray diffraction (XRD2) and optical absorption, spreading light on the peculiarities of the present growth technique, involving much faster solvent evaporation and film forming processes, and comparatively much more ordered strutures with less need of thermal annealing processes. The power conversion efficiency (PCE) under AM 1.5G solar simulation obtained for devices deposited from DCB as compared to those deposited from CLF, showed significant improvement, in fair agreement with what was found by the overall characterization of the physical properties.

During the chronic stage of Chagas disease a 160 kDa antigen appears in the blood of patients and remains detectable many years after the onset of the disease. This antigen is secreted by the trypomastigote form of the parasite while it is undetectable in the epimastigote form. We report here that the chronic 160 kDa exoantigen is encoded by a gene family (CEA 160 family). We describe the cloning and partial nucleotide sequence of a gene (CEA 160–1) belonging to the CEA160 family. Comparison of the gene sequence with other sequences present in the databases revealed homologies with several Trypanosoma cruzi surface antigens. Highest amino acid identity (59%) was with members of a family containing epitopes that mimic nervous tissues (Van Voorhis et al. 1993). Another related group (18–22% amino acid identity) comprises proteins of 85 or 160 kDa sharing an amino acid motif that is conserved among bacterial neuraminidases (Fouts et al. 1991; Pollevick et al. 1991; Kahn et al. 1991; Takle & Cross, 1991; Franco et al. 1993). The amino acid identities with the different antigens were not homogeneously distributed. Regions of higher identity (40–60%) were grouped in the central region of each protein.

Nanocrystalline SnO2 thin films were synthesized by Chemical Vapor Deposition on Si(100) and Al2O3 substrates using bis(diethylamino)dimethylstannane(IV) [(CH3)2Sn(N(C2H5)2)2] as precursor. Film growth was performed at 400-500°C in an O2(H2O)+N2 atmosphere, with the aim of studying the effects of the synthesis conditions on the coating properties. The sample chemical composition and surface morphology were analyzed by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM), while their structural features were investigated by Glancing Incidence X-ray Diffraction (GIXRD) and X-ray Reflectivity (XRR). In this paper, the attention is focused on the interplay between film nanostructure and morphology, with particular regard to the influence of the growth surface.

Amorphous silicon–nitrogen (a–Si1−xNx:H) alloys, thin films, and multilayers deposited by ultrahigh-vacuum plasma-enhanced chemical vapor deposition were studied and modeled by x-ray reflectivity (XRR) measurements. The analysis of XRR data obtained from the single-layer samples allowed us to calculate the density, thickness, and interface roughness of each layer. To check the deposition parameters, the deviation (tnom – texp)/(tnom) of the measured thickness texp from the nominal thickness tnom was evaluated. Based on these results, a simulation of a multilayer film, obtained by deposition alternating stoichiometric and substoichimetric layers was carried out. It is shown that the best fitting is obtained by introducing into the XRR calculation a thickness distribution with a standard deviation related to the deviation (tnom – texp)/(tnom) estimated for the single layers.

The effects of doping on the morphological and microstructural properties of TiO2 nanopowders produced by laser pyrolysis were investigated mainly by x-ray diffraction (XRD) and electron microscopy. Samples of TiO2 powders were prepared by doping with different trivalent cations (Al and Ga). The powders were calcined at different temperatures in the range 400–1000 °C for 18 h, as well as at constant T = 700 °C up to 160 h. After each thermal treatment, XRD patterns were collected. The analysis of XRD patterns allowed us to estimate the microstrains and average crystallite size and to observe the evolution of the microstructural parameters with temperature. Both Al and Ga inhibited the crystallite growth of TiO2 anatase and the rutile phases, this effect being larger in the Al-doped powders.

TiO2and W:TiO2 thin films have been prepared by a chemically modified sol-gel technique, that implies hydrolysis and condensation of tetraethylortotitanate in the presence of a polymer dissolved in ethanol. Oxide-polymer films were deposited by dip-coating. Annealing at 500°C results in nanosized structurally stable oxides films. For doping tungsten(V)ethoxide was used in concentration that led to a final W/Ti atomic ratio of 1/33, 5/33, 10/33. The morphological and structural characteristics of thin films were studied through microraman, GIXRD, SEM and TEM. A microstructural comparison between pure and doped TiO2 layers is reported. Ethanol and methanol sensing properties are tested.

The kinetics of phase transitions and phase segregation induced by annealing temperature on the Ti–W–O gas-sensing layer was studied by x-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The main goal was to identify, on the basis of kinetics studies, structurally stable Ti–WO3 thin film phases and compare their response to polluting gases in order to determine possible correlations between structural and electrical properties of the sensing layers.

The influence of the niobium content on the anatase-to-rutile phase transition in nanopowders of Nb–Ti oxides was studied and the changes in the particle size and microstrain distribution obtained at different temperatures were analyzed. A correlation is found between the initial microstructure in the Ti1 – xNbxO2 (x = 0.03, 0.2) powder and the niobium content. The presence of Nb was found to inhibit the growth of both the anatase and the rutile phases.

Thin films of the Ti-W-O system grown by r.f. reactive sputtering from a Ti-W (10%–90% weight) target have been studied by Raman and microraman spectroscopy, X-ray diffraction and scanning electron microscopy with the aim to investigate their microstructural and morphological properties. To this purpose, the kinetics of structural transformations at different temperatures (600 °C, and 800 °C) have been studied, and the effect of Ti on the WO3 lattice has been singled out. The results show that annealing at different temperatures induces a microstructural evolution from the amorphous phase of the as-deposited thin film to WO3 crystalline phases via an intermediate cubic disordered phase of WO3. The effect of Ti on this cubic phase and on the thin film morphology is also investigated with the aid of microraman and scanning electron microscopy analysis. The results show that two distinct phases arise upon long annealing treatments; namely, small crystallites belonging to the WO3 monoclinic phase are dispersed on a layer composed of a disordered cubic WO3 phase with a high Ti content.

Microraman and scanning electron microscopy studies have been performed on pure TiO2 and Nb-Ti-O nanopowders obtained by laser induced synthesis. The effect of Nb content on the temperature of the anatase to rutile phase transformation, induced by annealing in air at different temperatures, has been evidenced and related to the changes in the particle size distributions obtained from a Fourier analysis of the X-ray diffraction patterns.